But despite the likelihood the ASADA findings will not be revealed for months, midfielder Brent Stanton said the Bombers were confident the club's hierarchy was dedicated to proving the players' innocence.

"We go in [to the club] every day and I have no doubt, and all the players have full faith, in David Evans, Ian Robson and James Hird that they're looking after the off-field stuff," Stanton told AFL.com.au.

"We have full faith and confidence in the football club that they have our best interests at heart."

The AFL's deputy chief executive Gillon McLachlan in February said it was possible players may have been administered prohibited supplements "without their knowledge or consent."

Nearly four weeks after the investigation started, Stanton said the return of the NAB Cup, and the impending home and away season, had lifted spirits and sharpened the focus of the Bombers.

"To say that we're not worried might not be the right sort of term or context, but it's a part of what we have to go through and we've opened up our doors for this investigation," the 26-year-old said.

"The players are pretty upbeat. We get to do what we love day-in, day-out and that's play football.

"Our pre-season has been pretty solid since starting back last November and the games are starting, so I think the mood has picked up a bit and we're just excited to play football again."

Stanton, a member of Essendon's leadership group and the fourth-most experienced player at the club, said he was shocked when details of the investigation emerged.

"It sort of came out of the blue and we just had to deal with it at that stage. We didn't know much about it and we still probably don't because it's a federal investigation and all the information they've got we sort of don't know," he said.

"Our main focus is on round one but every time we get to run out on the football field the biggest challenge is to keep on improving as a football side."